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Numerical Study of Combustion of H2-O2 Cryogenic Propellant under Supercritical Condition

Barani, Ehsan | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48472 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Mardani, Amir
  7. Abstract:
  8. In order to improve performance and optimize design of high pressure combustion devices such as liquid rocket engine, gas turbine engine, and diesel engine there is a need for comprehensive understanding of injection, mixing and combustion in supercritical condition. Under this condition chamber pressure is higher than critical pressure of fuel and oxidizer. The characteristic of supercritical condition, include changing thermophysical properties such as density, CP, and compressibility factor. Therefore under this condition ideal state equation cannot correctly predict the mentioned properties. These characteristics make supercritical combustion different from other combustion regimes. Furturemore input fuel or oxydizer are in cryogenic condition, because of very high temperature difference between inlet flow into chamber and chamber temperature additional complexibility to flow field. In the present study, in the first step cryogenic nitrogen jet injected into environment containing nitrogen, in RCM01 laboratory chamber without considering combustion with different turbulent models and with different real gas state equation, simulated with RANS method and steady state and axisymmetric assumption. In order to study supercritical combustion, combustion of cryogenic propellant hydrogen-oxygen in RCM03 laboratory chamber with EDC combustion model and by using Burke chemical mechanism, with RANS model, simulation is made by using by using different turbulent models and different state equations under axisymmetric and steady state condition. Simulation results are compared with existing laboratory data. In both chambers different turbulent models and state equations were considered and the most suitable was selected. Combustion structure in supercritical condition was studied and effect of mechanism and pressure on flame shape was studied. Dense oxygen core during transition from critical point experiences severe density gradient and severe change of CP (pseudo boiling). Therefore correct prediction of critical transition zone is important for flame structure. Results show that selection of turbulent model has an effect on mixing layer dense core transition. Hydrogen-oxygen flame structure is different from subcritical condition in supercritical condition and during transcritical dense oxygen core causes flow expansion. Additionally structure of flow field is controlled by two vortices which result from extreme expansion of oxygen dense core and high velocity of inlet gaseous hydrogen into chamber. Chamber pressure increase delays transcritical condition and also increases flame length and length of secondary vortex and decreases expansion zone
  9. Keywords:
  10. Pressure Effect ; Mixing Process ; Supercritical Condition ; Turbulence Model ; Cryogenic Propellant ; Supercritical Combustion ; Real States Equation ; Cryogenic Propellant Hydrogen-Oxygen

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